Production of ${^{180\rm{m}}}$Hf in photoproton reaction ${^{181}}$Ta$(γ,p)$ at energy $E_{\rm{γmax}}$ = 35-95 MeV
The production of the $^{180\rm{m}}\rm{Hf}$ nuclei in the photoproton reaction ${^{181}\rm{Ta}}(γ,p)$ was studied at end-point bremsstrahlung energies $E_{\rm{γmax}}$ = 35-95 MeV. The experiment was performed at the electron linear accelerator LUE-40 NSC KIPT with the use of the $γ$ activation and off-line $γ$-ray spectroscopy. The experimental values of the bremsstrahlung flux-averaged cross-sections $\langle{σ(E_{\rm{γmax}})}\rangle_{\rm{m}}$ for the ${^{181}\rm{Ta}}(γ,p)^{180\rm{m}}\rm{Hf}$ reaction were determined, and at $E_{\rm{γmax}} > 55$ MeV obtained for the first time. The measured values, also as the literature data, are significantly exceed the theoretical flux-averaged cross-sections $\langle{σ(E_{\rm{γmax}})}\rangle_{\rm{th}}$. The $\langle{σ(E_{\rm{γmax}})}\rangle_{\rm{th}}$ values were calculated using the cross-section $σ(E)$ computed with the TALYS1.95 code for six different level density models. A comparative analysis of the calculated total cross-sections for the reactions ${^{181}\rm{Ta}}(γ,p)^{180}\rm{Hf}$ and ${^{181}\rm{Ta}}(γ,n)^{180}\rm{Ta}$ was performed. It was shown that the photoproton $(γ,p)$ to photoneutron $(γ,n)$ strength ratio is consistent with the estimates based on the isospin selection rules and the value from the $(e,e'p)$ experiment.